Traffic data imputation is essential in smart cities and the Internet of Things (IoT). Tensor completion is an efficient method for traffic data imputation. However, these methods overlook the integration of contextua...
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Traffic data imputation is essential in smart cities and the Internet of Things (IoT). Tensor completion is an efficient method for traffic data imputation. However, these methods overlook the integration of contextual and spatial information, which are important for traffic data imputation. Hence, this study proposes a novel tensor completion method leveraging contextual and spatial information for sparse traffic data imputation (STDI). Initially, we develop a model for STDI, treating traffic data as tensors and applying tensor completion for imputing missing values. Then, to account for contextual information, we compute the contextual scores of roads and reorganize the road indices according to the scores. Additionally, we utilize the Laplacian matrix to reveal spatial information and optimize the objective function to enhance imputation accuracy. Finally, we design a parallel algorithm for STDI on GPU for efficient computation. Extensive experiments demonstrate that the proposed method is superior to existing methods.
Community detection in social networks is the process of identifying the cohesive groups of similar nodes. Detection of these groups can be helpful in many applications, such as finding networks of protein interaction...
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Community detection in social networks is the process of identifying the cohesive groups of similar nodes. Detection of these groups can be helpful in many applications, such as finding networks of protein interaction in biological networks, finding the users of similar mind for ads and suggestions, finding a shared research field in collaborative networks, analyzing public health, future link prediction in social networks, analyzing criminology, and many more. However, with the increase in the number of profiles and content shared on social media platforms, the analysis is often time-consuming and exhaustive. In order to speed up and optimize the community detection process, parallel processing and Shared/Distributed memory techniques are widely used. Despite community detection has widespread use in social networks, no attempt has ever been made to compile and systematically discuss research efforts on the emerging subject of identifying parallel and distributed methods for community detection in social networks. Most of the surveys described the serial algorithms used for community detection. Our survey work comes under the scope of new design techniques, exciting or novel applications, components or standards, and applications of an educational, transactional, and co-operational nature. This paper accommodates and presents a systematic literature review with state-of-the-art research on the application of parallel processing and Shared/Distributed techniques to determine communities for social network analysis. Advanced search strategy has been performed on several digital libraries for extracting several studies for the review. The systematic search landed in finding 3220 studies, among which 65 relevant studies are selected after conducting various screening phases for further review. The application of parallel computing, shared memory, and distributed memory on the existing community detection methodologies have been discussed thoroughly. More specifically,
Influence Maximization (IM) is vital in viral marketing and biological network analysis for identifying key in-fluencers. Given its NP-hard nature, approximate solutions are employed. This paper addresses scalability ...
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We consider the stochastic dual dynamic programming (SDDP) algorithm - a widely employed algorithm applied to multistage stochastic programming - and propose a variant using experience replay - a batch learning techni...
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We consider the stochastic dual dynamic programming (SDDP) algorithm - a widely employed algorithm applied to multistage stochastic programming - and propose a variant using experience replay - a batch learning technique from reinforcement learning. To connect SDDP with reinforcement learning, we cast SDDPas aQ-learning algorithm and describe its application in both risk-neutral and risk-averse settings. We demonstrate the superiority of the algorithm over conventional SDDP by benchmarking it against PSR's SDDP software using a large-scale instance of the long-term planning problem of inter-connected hydropower plants in Colombia. We find that SDDP with batch learning is able to produce tighter optimality gaps in a shorter amount of time than conventional SDDP. We also find that batch learning improves the parallel efficiency of SDDP backward passes.
Large-scale learning algorithms are essential for modern data collections that may have billions of data points. Here, we study the design of parallel k-clustering algorithms, which include the k-median, k-medoids, an...
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Large-scale learning algorithms are essential for modern data collections that may have billions of data points. Here, we study the design of parallel k-clustering algorithms, which include the k-median, k-medoids, and k-means clustering problems. We design efficient parallel algorithms for these problems and prove that they still compute constant-factor approximations to the optimal solution for stable clustering instances. In addition to our theoretic results, we present computational experiments that show that our k-median and k-means algorithms work well in practice-we are able to find better clusterings than state-of-the-art coreset constructions using samples of the same size.
In this work we present a parallel algorithm for the Concurrent Atomistic Continuum (CAC) formulation that can be integrated into existing molecular dynamics codes. The CAC methodology is briefly introduced and its pa...
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In this work we present a parallel algorithm for the Concurrent Atomistic Continuum (CAC) formulation that can be integrated into existing molecular dynamics codes. The CAC methodology is briefly introduced and its parallel implementation in LAMMPS is detailed and then demonstrated through benchmarks that compare CAC simulation results with corresponding all-MD (molecular dynamics) results. The parallel efficiency of the algorithm is demonstrated when simulating systems represented by both atoms and finite elements. The verification benchmarks include dynamic crack propagation and branching in a Si single crystal, wave propagation and scattering in a Si phononic crystal, and phonon transport through the phase interface in a PbTe/PbSe heteroepitaxial system. In each of these benchmarks the CAC algorithm is shown to be in good agreement with MD-only models. This parallel CAC algorithm thus offers one of the first scalable multiscale material simulation methodologies that relies solely on atomic-interaction models. (c) 2022 Published by Elsevier Inc.
The Branch-and-Bound(B&B) algorithm is an effective method for solving the Mixed Integer Linear Programming (MILP) problem. Its performance significantly impacts the overall performance of the MILP solver Addition...
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Since automatic algorithm configuration methods have been very effective, recently there is increasing research interest in utilizing them for automatic solver construction, resulting in several notable approaches. Fo...
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Since automatic algorithm configuration methods have been very effective, recently there is increasing research interest in utilizing them for automatic solver construction, resulting in several notable approaches. For these approaches, a basic assumption is that the given training set could sufficiently represent the target use cases such that the constructed solvers can generalize well. However, such an assumption does not always hold in practice since in some cases, we might only have scarce and biased training data. This article studies effective construction approaches for the parallel algorithm portfolios that are less affected in these cases. Unlike previous approaches, the proposed approach simultaneously considers instance generation and portfolio construction in an adversarial process, in which the aim of the former is to generate instances that are challenging for the current portfolio, while the aim of the latter is to find a new component solver for the portfolio to better solve the newly generated instances. Applied to two widely studied problem domains, that is, the Boolean satisfiability problems (SAT) and the traveling salesman problems (TSPs), the proposed approach identified parallel portfolios with much better generalization than the ones generated by the existing approaches when the training data were scarce and biased. Moreover, it was further demonstrated that the generated portfolios could even rival the state-of-the-art manually designed parallel solvers.
The Single Source Shortest Path (SSSP) problem is a classic graph theory problem that arises frequently in various practical scenarios;hence, many parallel algorithms have been developed to solve it. However, these al...
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The Single Source Shortest Path (SSSP) problem is a classic graph theory problem that arises frequently in various practical scenarios;hence, many parallel algorithms have been developed to solve it. However, these algorithms operate on static graphs, whereas many real-world problems are best modeled as dynamic networks, where the structure of the network changes with time. This gap between the dynamic graph modeling and the assumed static graph model in the conventional SSSP algorithms motivates this work. We present a novel parallel algorithmic framework for updating the SSSP in large-scale dynamic networks and implement it on the shared-memory and GPU platforms. The basic idea is to identify the portion of the network affected by the changes and update the information in a rooted tree data structure that stores the edges of the network that are most relevant to the analysis. Extensive experimental evaluations on real-world and synthetic networks demonstrate that our proposed parallel updating algorithm is scalable and, in most cases, requires significantly less execution time than the state-of-the-art recomputing-from-scratch algorithms.
center dot Currently, domain propagation in state-of-the-art MIP solvers is single thread only. center dot The paper presents a novel, efficient GPU algorithm to perform domain propagation. center dot Challenges are d...
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center dot Currently, domain propagation in state-of-the-art MIP solvers is single thread only. center dot The paper presents a novel, efficient GPU algorithm to perform domain propagation. center dot Challenges are dynamic algorithmic behavior, dependency structures, sparsity patterns. center dot The algorithm is capable of running entirely on the GPU with no CPU involvement. center dot We achieve speed-ups of around 10x to 20x, up to 180x on favorably-large instances.
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